The San Francisco 49ers are experimenting with a variety of changes along their offensive line this offseason. And it remains the lone unit with the most question marks heading into 2017.

Yes, the San Francisco 49ers offensive line was much better in 2016 than it was the year prior.

Fans didn't have to deal with watching former Niners linemen Jordan Devey or Erik Pears act as team turnstiles like they did in 2015. And yet this moderately improved 2016 O-line wasn't exactly stellar. According to Football Outsiders, San Francisco's O-line ranked 30th in pass protection and dead last in run support.

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The 2017 NFL Draft didn't provide a lot of options for general manager John Lynch to make notable upgrades. This year's draft class simply wasn't talented or deep enough.

At least there's something resembling competition this offseason, which is good. And yet there still may be a few problems facing this group as the regular season draws nearer.

So let's look at each of the positions and see where the potential problems may be.

Offensive Tackle

Aside from his age, there isn't much to worry about with Staley. In an ideal world, the Niners would have an adequate swing tackle capable of mastering head coach Kyle Shanahan's outside-zone blocking scheme. There are a few options we'll get to in a moment, but let's focus on the right tackle position first.

Brown, and his massive 6-foot-8, 355-pound frame, isn't an ideal zone-blocking lineman. While he's good at pass protection, his problematic run-blocking may be a major issue, as it was last year. According to Pro Football Focus, Brown's run-blocking grade in 2016 netted a lowly 39.0 mark -- 72nd out of 79 qualifiers in this category. Brown won the starting job last year almost by default.

As such, the Gilliam acquisition makes sense. Gilliam is much more nimble on his feet but, according to the Santa Rosa Press Democrat's Grant Cohn, Gilliam was having all kinds of trouble blocking edge rushers Arik Armstead and Ronald Blair during the Niners' first week of OTAs. Gilliam isn't a good pass blocker, so he doesn't appear to be a likely option for either tackle spot. And he may be a bit of a liability as a swing tackle too, which makes Beadles the likely favorite to earn such a job.

Offensive Guard

With a 40.2 overall PFF grade last year, Beadles was certainly among the worst 49ers starters in 2016.

There isn't any guarantee he earns a starting job this season, although I have a hunch he sticks around on the roster because of his ability to play tackle and all three interior O-line positions. San Francisco may wind up using him as an uber backup of sorts.

His opposite number, Garnett, had a disappointing rookie season last year. His 42.4 PFF grade wasn't much better than Beadles, and there are also questions as to how he'd fit in a zone-blocking scheme. As such, San Francisco is experimenting with him at both guard positions this offseason. Garnett primarily played at left guard at Stanford, so one might assume the better fit is there.

"You need some versatility," Shanahan said of Garnett, via the team's website. "But, it's something we want him to workout at both and hopefully we'll put him in a spot that's the best for him and hopefully it will be the best for the team."

Ideally, the left spot would be the best fit. But this positioning tends to be reserved for the team's best guard, and Garnett is far from proving he's a solid piece. And this might describe why San Francisco brought in Fusco, whose 52.8 PFF grade a year ago is already better than what both Garnett and Beadles posted in 2016.

Center

The 49ers do have somewhat of a likable problem at center this offseason.

Adding Zuttah, via a trade with the Baltimore Ravens, means Kilgore won't be the shoo-in at center. That's a good thing. Kilgore has an injury history and has missed a combined 23 games since taking over starting duties in 2014. And yet he has still been one of the 49ers' better O-linemen the past few years.

Centers are of utmost importance to a Shanahan offense, so one has to think the Zuttah pickup is an indication who the head coach wants starting at this position.

But the good news is the loser of this starting battle could kick out to the guard spot. And former Los Angeles Rams center Tim Barnes keeps both Zuttah and Kilgore on their toes.

Starting Lineup Prediction

LT -- Joe Staley

LG -- Daniel Kilgore

C -- Jeremy Zuttah

RG -- Joshua Garnett

RT -- Trent Brown

As noted earlier, Staley is the only lock to start. The rest of the O-line has some flexibility, which is good, but perhaps only Zuttah starting at center is ideal.

Kilgore gets the nod over Beadles at left guard simply because the former has proven to be a more worthwhile option. Beadles could rebound from an otherwise forgetful 2016 campaign, but it seems more likely the 49ers keep him as a primary backup. There are surely worse options out there.

Despite a problematic rookie year, Garnett still starts in 2017. He recently earned praise from his former head coach at Stanford, David Shaw, who thinks Garnett will wind up being a key cog in Shanahan's offense. A guess would have the Niners being a little more patient with Garnett, given the first-round NFL Draft investment made in him a year ago. That won't go far, but it's something to consider.

Gilliam isn't going to overtake Brown. Beadles could, in theory, but Brown is a much better option in pass protection. Yet it doesn't take too much to identify an issue here. With Brown's struggles in run support, Shanahan will likely be forced to send the rushing attack to the left side of the line, taking away a key portion of the field on the ground.

The 49ers made some changes up front this offseason -- part of the wholesale overhaul needed to get this team back on track.

And yet San Francisco's O-line is far from a perfected unit. It's likely Lynch will make more moves just under a year from now when more promising options are available in either the NFL Draft or free agency.

In the meantime, the Niners will roll on with what they've got and hope it pans out.

Peter Panacy has been writing about the 49ers since 2011 for outlets like Bleacher Report, Niner Noise and 49ers Webzone and is occasionally heard as a guest on San Francisco's 95.7 FM The Game. Feel free to follow him, or direct any inquiries to @PeterPanacy on Twitter.

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